As ppl have said, it’s usually a kinda shitty job. Sales jobs also don’t have the benefit of getting to complain or make fun of the company to friends so you have to be ‘always on’ or actually bought into the thing you’re selling. That some calendar app greatly improves workplace productivity is not that hard a pill to swallow if it pays the bills, but the field definitely has an athletic polo kind of vibe to it.

I don’t think Marx differentiated sales people from other jobs, but I might be wrong.